- yast2-country has been split into two packages recently
(yast2-country and yast2-country-data). Language.ycp is newly in
yast2-country-data.
- Make sure you have yast2-country-data package installed.
- (Wrong dependencies in some YaST RPM?)
- If you have updated yast2-country to a new verson, Language.ycp
probably got deleted.

* Caught invalid bytecode in SlideShow.ybc

- Probably old yast2-packager (SlideShow is part of it). You need to
update that package too.
- Maybe caused be the very same mistake by wrong RPM dependencies.

You can still use 'zypper' to update your packages when YaST is broken :)